The present invention relates to an improved dome-shaped head portion for the pistons of an internal combustion engine which allows the engine to transfer the air-fuel mixture across and around the piston head more efficiently when the engine goes from the exhaust to the intake stroke.
In a conventional four-stroke internal combustion engine, when the piston is at top dead center between the exhaust and intake strokes, both the intake and exhaust valves are open. The exhaust valve closes as the piston begins the intake stroke. Atmospheric pressure forces the air-fuel mixture through the intake port to fill the void created by the displacement of the piston in the combustion chamber. When the piston reaches bottom dead center, the intake valve closes. The engine then goes through the compression and explosion strokes. When the piston is at bottom dead center after the explosion stroke, the exhaust valve opens. The piston then rises on the exhaust stroke, expelling the burned gases from the combustion chamber. When the piston is at top dead center, both the intake and exhaust valves are again open.